Purpose: The aims of this study were (1) to compare the areas of metal-induced artifacts and definition of periprosthetic structures between patients scanned with the slice-encoding metal artifact correction and view-angle tilting (SEMAC-VAT) turbo-spin-echo (TSE) prototype and those scanned with the standard TSE magnetic resonance (MR) sequences and (2) to further clarify the superiority of the SEMAC-VAT MR imaging technique at detecting lesions in patients after total hip arthroplasty (THA), compared with digital radiography (DR).
Materials and methods: A total of 38 consecutive patients who underwent THA were referred to MR imaging at our institution. All patients suffered from chronic hip pain postoperatively. Twenty-three patients of the 38 were examined with a 1.5-T MR scanner using a SEMAC-VAT TSE prototype and standard TSE sequence, and the remaining 15 patients were examined with the same 1.5-T MR scanner, but using the SEMAC-VAT TSE prototype only. The traditional DR imaging was also performed for all patients. Two radiologists then independently measured the area of metal-induced artifacts and evaluated the definition of both the acetabular and femoral zones based on a three-point scale. Finally, the positive findings of chronic hip pain after THA based on SEMAC-VAT TSE MR imaging and traditional DR imaging were compared and analysed.
Results: The areas of metal-induced artifacts were significantly smaller in the SEMAC-VAT TSE sequences than those in the standard TSE sequences for both the T1-weighted (p < 0.001) and T2-weighted (p < 0.001) turbo inversion recovery magnitude images. In addition, 28 patients showed a series of positive signs in the SEMAC-VAT images that were not observed in the traditional DR images.
Conclusion: Compared with the standard TSE MR imaging, SEMAC-VAT MR imaging significantly reduces metal-induced artifacts and might successfully detect most positive signs missed in the traditional DR images.
Translational potential of this article: The main objective of this research was to show that MR sequences from the SEMAC-VAT TSE prototype provide a significant advantage at detecting lesions in patients after THA because of the excellent soft-tissue resolution of the MR imaging. SEMAC-VAT MR can evaluate chronic hip pain after THA and determine the cause, which can help the clinician decide on whether a surgical revision is needed.
Keywords: Metal artifact; Slice-encoding metal artifact correction and view-angle tilting magnetic resonance; Total hip arthroplasty.